Camshaft phasers for varying the phase relationship between the pistons and the valves of an internal combustion engine are well known and need not be described in greater detail here. In a vane-type phaser, a rotor having a plurality of spaced-apart vanes is rotatably disposed within a stator having a plurality of spaced-apart lobes. Advance and retard oil chambers are thus formed between the vanes and the lobes.
A problem exists in prior art vane-type camshaft phasers wherein the lobes and vanes typically are arranged generally symmetrically about the phaser axis. The rotor vanes may be bent or otherwise damaged by high-impact contact with the lobes during an uncontrolled event such as at engine start-up. Further, since the included angle of the rotor vanes and the stator lobes, as cast, determine the starting point and the total angular displacement of the cam phaser in the prior art, the starting point of the rotor and angular displacement of the phaser can not be precisely controlled because of casting tolerances.
Therefore, what is needed is a means for preventing phaser damage from rotor/stator contact.
Also what is needed is a means for accurately controlling the starting position and displacement angle of the rotor.
It is a principal object of the present invention to provide an improved camshaft phaser wherein damage to vanes and lobes is prevented during high-impact events and a means for adjusting the starting position and angular displacement of the rotor is provided.